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Loss of P-glycoprotein expression in hematopoietic stem cells does not improve responses to imatinib in a murine model of chronic myelogenous leukemia

Loss of P-glycoprotein expression in hematopoietic stem cells does not improve responses to... Selective inhibition of the BCR/ABL tyrosine kinase by imatinib has become a first-line therapy for chronic myelogenous leukemia (CML). However, BCR/ABL-positive progenitors often persist despite treatment, and relapse associated with resistance to imatinib has been described in many patients with advanced disease. Drug efflux by P-glycoprotein (P-gp), as well as point mutations in BCR/ABL oncoprotein, has been implicated in the mechanism of resistance to imatinib. In this study, we established a murine transplantation model of CML-like myeloproliferative disease using Mdr1a/1b-null mice and analyzed the effects of loss of P-gp on resistance to imatinib. We found that mice transplanted with Mdr1a/1b-null bone marrow (BM) that had been transduced with a BCR/ABL retroviral vector displayed similar responses to imatinib, compared with those transplanted with BCR/ABL-transduced wild-type BM. In the absence of P-gp, the incidence and latency of disease in secondary recipients was not changed in imatinib-treated mice, relative to wild-type controls. Furthermore, K562 cells engineered to overexpress P-gp remained sensitive to imatinib-induced growth inhibition and cell death. Together, our findings suggest that P-gp expression in hematopoietic stem cells does not significantly contribute to imatinib resistance in CML. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Leukemia Springer Journals

Loss of P-glycoprotein expression in hematopoietic stem cells does not improve responses to imatinib in a murine model of chronic myelogenous leukemia

Zong, Y; Zhou, S; Sorrentino, B P
Leukemia , Volume 19 (9) – Jul 7, 2005
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References (40)

Publisher
Springer Journals
Copyright
Copyright © 2005 by Nature Publishing Group
Subject
Medicine & Public Health; Medicine/Public Health, general; Internal Medicine; Intensive / Critical Care Medicine; Cancer Research; Oncology; Hematology
ISSN
0887-6924
eISSN
1476-5551
DOI
10.1038/sj.leu.2403853
Publisher site
See Article on Publisher Site

Abstract

Selective inhibition of the BCR/ABL tyrosine kinase by imatinib has become a first-line therapy for chronic myelogenous leukemia (CML). However, BCR/ABL-positive progenitors often persist despite treatment, and relapse associated with resistance to imatinib has been described in many patients with advanced disease. Drug efflux by P-glycoprotein (P-gp), as well as point mutations in BCR/ABL oncoprotein, has been implicated in the mechanism of resistance to imatinib. In this study, we established a murine transplantation model of CML-like myeloproliferative disease using Mdr1a/1b-null mice and analyzed the effects of loss of P-gp on resistance to imatinib. We found that mice transplanted with Mdr1a/1b-null bone marrow (BM) that had been transduced with a BCR/ABL retroviral vector displayed similar responses to imatinib, compared with those transplanted with BCR/ABL-transduced wild-type BM. In the absence of P-gp, the incidence and latency of disease in secondary recipients was not changed in imatinib-treated mice, relative to wild-type controls. Furthermore, K562 cells engineered to overexpress P-gp remained sensitive to imatinib-induced growth inhibition and cell death. Together, our findings suggest that P-gp expression in hematopoietic stem cells does not significantly contribute to imatinib resistance in CML.

Journal

Leukemia – Springer Journals

Published: Jul 7, 2005

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